1. Field of the Invention
This invention relates to a class of ligand or complex useful as catalysts for catalytically bleaching substrates with atmospheric oxygen, and as catalysts in the bleaching of textiles such as laundry fabrics whereby bleaching by atmospheric oxygen is catalysed after the treatment.
2. The Related Art
Peroxygen bleaches are well known for their ability to remove stains from substrates. Traditionally, the substrate is subjected to hydrogen peroxide, or to substances which can generate hydroperoxyl radicals, such as inorganic or organic peroxides. Generally, these systems must be activated. One method of activation is to employ wash temperatures of 60xc2x0 C. or higher. However, these high temperatures often lead to inefficient cleaning, and can also cause premature damage to the substrate.
A preferred approach to generating hydroperoxyl bleach radicals is the use of inorganic peroxides coupled with organic precursor compounds. These systems are employed for many commercial laundry powders. For example, various European systems are based on tetraacetyl ethylenediamine (TAED) as the organic precursor coupled with sodium perborate or sodium percarbonate, whereas in the United States laundry bleach products are typically based on sodium nonanoyloxybenzenesulfonate (SNOBS) as the organic precursor coupled with sodium perborate.
Precursor systems are generally effective but still exhibit several disadvantages. For example, organic precursors are moderately sophisticated molecules requiring multi-step manufacturing processes resulting in high capital costs. Also, precursor systems have large formulation space requirements so that a significant proportion of a laundry powder must be devoted to the bleach components, leaving less room for other active ingredients and complicating the development of concentrated powders. Moreover, precursor systems do not bleach very efficiently in countries where consumers have wash habits entailing low dosage, short wash times, cold temperatures and low wash liquor to substrate ratios.
Alternatively, or additionally, hydrogen peroxide and peroxy systems can be activated by bleach catalysts, such as by complexes of iron and the ligand N4Py (i.e. N, N-bis(pyridin-2-yl-methyl)-bis(pyridin-2-yl)methylamine) disclosed in WO95/34628, or the ligand Tpen (i.e. N, N, Nxe2x80x2, Nxe2x80x2-tetra(pyridin-2-yl-methyl)ethylenediamine) disclosed in WO97/48787. According to these publications, molecular oxygen may be used as the oxidant as an alternative to peroxide generating systems. However, no role in catalysing bleaching by atmospheric oxygen in an aqueous medium is reported.
It has long been thought desirable to be able to use atmospheric oxygen (air) as the source for a bleaching species, as this would avoid the need for costly hydroperoxyl generating systems. Unfortunately, air as such is kinetically inert towards bleaching substrates and exhibits no bleaching ability. Recently some progress has been made in this area. For example, WO 97/38074 reports the use of air for oxidising stains on fabrics by bubbling air through an aqueous solution containing an aldehyde and a radical initiator. A broad range of aliphatic, aromatic and heterocyclic aldehydes is reported to be useful, particularly para-substituted aldehydes such as 4-methyl-, 4-ethyl- and 4-isopropyl benzaldehyde, whereas the range of initiators disclosed includes N-hydroxysuccinimide, various peroxides and transition metal coordination complexes.
However, although this system employs molecular oxygen from the air, the aldehyde component and radical initiators such as peroxides are consumed during the bleaching process. These components must therefore be included in the composition in relatively high amounts so as not to become depleted before completion of the bleaching process in the wash cycle. Moreover, the spent components represent a waste of resources as they can no longer participate in the bleaching process.
Accordingly, it would be desirable to be able to provide a bleaching system based on atmospheric oxygen or air that does not rely primarily on hydrogen peroxide or a hydroperoxyl generating system, and that does not require the presence of organic components such as aldehydes that are consumed in the process. Moreover, it would be desirable to provide such a bleaching system that is effective in aqueous medium.
It may also be noted that the known art teaches a bleaching effect only as long as the substrate is being subjected to the bleaching treatment. Thus, there is no expectation that hydrogen peroxide or peroxy bleach systems could continue to provide a bleaching effect on a treated substrate, such as a laundry fabric after washing and drying, since the bleaching species themselves or any activators necessary for the bleaching systems would be assumed to be removed from the substrate, or consumed or deactivated, on completing the wash cycle and drying.
It would be therefore also be desirable to be able to treat a textile such that, after the treatment is completed, a bleaching effect is observed on the textile. Furthermore, it would be desirable to be able to provide a bleach treatment for textiles such as laundry fabrics whereby residual bleaching occurs when the treated fabric has been treated and is dry.
We have found a novel class of ligand or complex that is surprisingly effective in catalysing the bleaching of substrates using atmospheric oxygen or air.
Accordingly, in a first aspect, the present invention provides a ligand of the general formula (I): 
wherein R1, R2, and R3 independently represent a group selected from methyl, pyridin-2-yl, quinolin-2-yl, pyrazol-1-yl, 3,5-dimethylpyrazol-1-yl, N-methyl-amido, and N-isopropyl-amido; provided at least two of R1, R2 and R3 represent a coordinating group, the ligand being selected from:
1,4-bis(pyridin-2-ylmethyl)-7-ethyl-1,4,7-triazacyclononane;
1,4-bis(quinolin-2-ylmethyl)-7-ethyl-1,4,7-triazacyclononane;
1,4-bis(pyrazol-1-ylmethyl)-7-ethyl-1,4,7-triazacyclononane;
1,4-bis(3,5-dimethylpyrazol-1-ylmethyl)-7-ethyl-1,4,7-triazacyclononane;
1,4-bis(N-methylimidazol-2-ylmethyl)-7-ethyl-1,4,7-triazacyclononane;
1,4,7-tris(quinolin-2-ylmethyl)-1,4,7-triazacyclononane;
1,4-bis(N-isopropylacetamido)-7-ethyl-1,4,7-triazacyclononane; and
1,4-bis(N-methylacetamido)-7-ethyl-1,4,7-triazacyclononane.
In a second aspect, the present invention provides a complex of the ligand and a transition metal.
An advantage of the class of ligand and complex according to the present invention is that the complex can catalyse bleaching of a substrate by atmospheric oxygen, thus permitting its use in a medium such as an aqueous medium that is substantially devoid of peroxygen bleach or a peroxy-based or -generating bleach system. We have also found that complexes of this class are surprisingly effective in catalysing bleaching of the substrate by atmospheric oxygen after treatment of the substrate.
Advantageously, the ligand or complex according to the present invention permits all or the majority of the bleaching species in the medium (on an equivalent weight basis) to be derived from atmospheric oxygen. Thus, the medium can be made wholly or substantially devoid of peroxygen bleach or a peroxy-based or -generating bleach system. Furthermore, the complex is a catalyst for the bleaching process and, as such, is not consumed but can continue to participate in the bleaching process. Thus, the ligand or complex can provide a catalytically activated bleaching system which is based on atmospheric oxygen, is therefore both cost-effective and environmentally friendly. Moreover, a bleaching system can be provided that is operable under unfavourable wash conditions which include low temperatures, short contact times and low dosage requirements. Furthermore, the catalyst is effective in an aqueous medium and is therefore particularly applicable to bleaching of laundry fabrics. Therefore, whilst the catalyst according to the present invention may be used for bleaching any suitable substrate, the preferred substrate is a laundry fabric. Bleaching may be carried out by simply leaving the substrate in contact with the medium for a sufficient period of time. Preferably, however, the aqueous medium on or containing the substrate is agitated.
A further advantage is that, by enabling a bleaching effect even after the textile has been treated, the benefits of bleaching can be prolonged on the textile. Furthermore, since a bleaching effect is conferred to the textile after the treatment, the treatment itself, such as a laundry wash cycle, may for example be shortened. Moreover, since a bleaching effect is achieved by atmospheric oxygen after treatment of the textile, hydrogen peroxide or peroxy-based bleach systems can be omitted from the treatment substance.
The catalyst may be used as a preformed complex of the ligand and a transition metal. Alternatively, the catalyst may be formed from the free ligand that complexes with a transition metal already present in the water or that complexes with a transition metal present in the substrate. The composition may also be formulated as a composition of the free ligand or a transition metal-substitutable metal-ligand complex, and a source of transition metal, whereby the complex is formed in situ in the medium.
The ligand forms a complex with one or more transition metals, in the latter case for example as a dinuclear complex. Suitable transition metals include for example: manganese in oxidation states II-V, iron II-V, copper I-III, cobalt I-III, titanium II-IV, tungsten IV-VI, vanadium II-V and molybdenum II-VI.
The ligand forms a complex of the general formula (A1):
[MaLkXn]Ymxe2x80x83xe2x80x83(A1)
in which:
M represents a metal selected from Mn(II)-(III)-(IV)(V), Cu(I)-(II)-(III), Fe(II)-(III)-(IV)-(V), Co(I)-(II) -(III), Ti (II)-(III)-(IV), V(II)-(III)-(IV)-(V), Mo(II)-(III)-(IV)-(V)-(VI) and W(IV)-(V)-(VI), preferably selected from Fe(II)-(III)-(IV)-(V);
L represents a ligand as herein defined, or its protonated or deprotonated analogue;
X represents a coordinating species selected from any mono, bi or tri charged anions and any neutral molecules able to coordinate the metal in a mono, bi or tridentate manner, preferably selected from O2xe2x88x92, RBO22xe2x88x92, RCOOxe2x88x92, RCONRxe2x88x92, OHxe2x88x92, NO3xe2x88x92, NO, S2xe2x88x92, RSxe2x88x92, PO43xe2x88x92, PO3OR3xe2x88x92, H2O, CO32xe2x88x92, HCO3xe2x88x92, ROH, N(R)3, ROOxe2x88x92, O22xe2x88x92, O2xe2x88x92, RCN, Clxe2x88x92, Brxe2x88x92, OCNxe2x88x92, SCNxe2x88x92, CNxe2x88x92, N3xe2x88x92, Fxe2x88x92, Ixe2x88x92, ROxe2x88x92, ClO4xe2x88x92, and CF3SO3xe2x88x92, and more preferably selected from O2xe2x88x92, RBO22xe2x88x92, RCOOxe2x88x92, OHxe2x88x92, NO3xe2x88x92, S2xe2x88x92, RSxe2x88x92, PO34xe2x88x92, H2O, CO32xe2x88x92, HCO3xe2x88x92, ROH, N(R)3, Clxe2x88x92, Brxe2x88x92, OCNxe2x88x92, SCNxe2x88x92, RCN, N3xe2x88x92, Fxe2x88x92, Ixe2x88x92, ROxe2x88x92, ClO4xe2x88x92, and CF3SO3xe2x88x92;
Y represents any non-coordinated counter ion, preferably selected from ClO4xe2x88x92, BR4xe2x88x92, [MX4]xe2x88x92, [MX4]2xe2x88x92, PF6xe2x88x92, RCOOxe2x88x92, NO3xe2x88x92, ROxe2x88x92, N+(R)4, ROOxe2x88x92, O22xe2x88x92, O2xe2x88x92, Clxe2x88x92, Brxe2x88x92, Fxe2x88x92, Ixe2x88x92, CF3SO3xe2x88x92, S2O62xe2x88x92, OCNxe2x88x92, SCNxe2x88x92, H2O, RBO22xe2x88x92, BF4xe2x88x92 and BPh4xe2x88x92, and more preferably selected from ClO4xe2x88x92, BR4xe2x88x92, [FeCl4]xe2x88x92, PF6xe2x88x92, RCOOxe2x88x92, NO3xe2x88x92, ROxe2x88x92, N+(R)4, Clxe2x88x92, Brxe2x88x92, Fxe2x88x92, Ixe2x88x92, CF3SO3xe2x88x92, S2O6xe2x88x92, OCNxe2x88x92, SCNxe2x88x92, H2O and BF4xe2x88x92;
a represents an integer from 1 to 10, preferably from 1 to 4;
k represents an integer from 1 to 10;
n represents an integer from 1 to 10, preferably from 1 to 4;
m represents zero or an integer from 1 to 20, preferably from 1 to 8; and
each R independently represents a group selected from hydrogen, hydroxyl, xe2x80x94Rxe2x80x2 and xe2x80x94ORxe2x80x2, wherein Rxe2x80x2=alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl or a carbonyl derivative group, Rxe2x80x2 being optionally substituted by one or more functional groups E, wherein E independently represents a functional group selected from xe2x80x94F, xe2x80x94Cl, xe2x80x94Br, xe2x80x94I, xe2x80x94OH, xe2x80x94ORxe2x80x2, xe2x80x94NH2, xe2x80x94NHRxe2x80x2, xe2x80x94N(Rxe2x80x2)2, xe2x80x94N(Rxe2x80x2)3+, xe2x80x94C(O)Rxe2x80x2, xe2x80x94OC(O)Rxe2x80x2, xe2x80x94COOH, xe2x80x94COOxe2x88x92 (Na+, K+), xe2x80x94COORxe2x80x2, xe2x80x94C(O)NH2, xe2x80x94C(O)NHRxe2x80x2, xe2x80x94C(O)N(Rxe2x80x2)2, heteroaryl, xe2x80x94Rxe2x80x2, xe2x80x94SRxe2x80x2, xe2x80x94SH, xe2x80x94P(Rxe2x80x2)2, xe2x80x94P(O)(Rxe2x80x2)2, xe2x80x94P(O)(OH)2, xe2x80x94P(O)(ORxe2x80x2)2, xe2x80x94NO2, xe2x80x94SO3H, xe2x80x94SO3xe2x88x92(Na+, K+), xe2x80x94S(O)2Rxe2x80x2, xe2x80x94NHC(O)Rxe2x80x2, and xe2x80x94N(Rxe2x80x2)C(O)Rxe2x80x2, wherein Rxe2x80x2 represents cycloalkyl, aryl, arylalkyl, or alkyl optionally substituted by xe2x80x94F, xe2x80x94Cl, xe2x80x94Br, xe2x80x94I, xe2x80x94NH3+, xe2x80x94SO3H, xe2x80x94SO3xe2x88x92(Na+, K+) , xe2x80x94COOH, xe2x80x94COOxe2x88x92(Na+, K+) , xe2x80x94P(O)(OH)2, or xe2x80x94P(O) (Oxe2x88x92(Na+, K+))2, and preferably each R independently represents hydrogen, optionally substituted alkyl or optionally substituted aryl, more preferably hydrogen or optionally substituted phenyl, naphthyl or C1-4-alkyl.
The counter ions Y in formula (A1) balance the charge z on the complex formed by the ligand L, metal M and coordinating species X. Thus, if the charge z is positive, Y may be an anion such as RCOOxe2x88x92, BPh4xe2x88x92, ClO4xe2x88x92, BF4xe2x88x92, PF6xe2x88x92, RSO3xe2x88x92, RSO4xe2x88x92, SO42xe2x88x92, NO3xe2x88x92, Fxe2x88x92, Clxe2x88x92, Brxe2x88x92, or Ixe2x88x92, with R being hydrogen, optionally substituted alkyl or optionally substituted aryl. If z is negative, Y may be a common cation such as an alkali metal, alkaline earth metal or (alkyl)ammonium cation.
Suitable counter ions Y include those which give rise to the formation of storage-stable solids. Preferred counter ions for the preferred metal complexes are selected from R7COOxe2x88x92, ClO4xe2x88x92, BF4xe2x88x92, PF6xe2x88x92, RSO3xe2x88x92 (in particular CF3SO3xe2x88x92), RSO4xe2x88x92, SO42xe2x88x92, NO3xe2x88x92, Fxe2x88x92, Clxe2x88x92, Brxe2x88x92, and Ixe2x88x92, wherein R represents hydrogen or optionally substituted phenyl, naphthyl or C1-C4 alkyl.
It will be appreciated that the complex (A1) can be formed by any appropriate means, including in situ formation whereby precursors of the complex are transformed into the active complex of general formula (A1) under conditions of storage or use. Preferably, the complex is formed as a well-defined complex or in a solvent mixture comprising a salt of the metal M and the ligand L or ligand L-generating species. Alternatively, the catalyst may be formed in situ from suitable precursors for the complex, for example in a solution or dispersion containing the precursor materials. In one such example, the active catalyst may be formed in situ in a mixture comprising a salt of the metal M and the ligand L, or a ligand L-generating species, in a suitable solvent. Thus, for example, if M is iron, an iron salt such as FeSO4 can be mixed in solution with the ligand L, or a ligand L-generating species, to form the active complex. Thus, for example, the composition may formed from a mixture of the ligand L and a metal salt MXn in which preferably n=1-5, more preferably 1-3. In another such example, the ligand L, or a ligand L-generating species, can be mixed with metal M ions present in the substrate or wash liquor to form the active catalyst in situ. Suitable ligand L-generating species include metal-free compounds or metal coordination complexes that comprise the ligand L and can be substituted by metal M ions to form the active complex according the formula (A1).
The catalysts according to the present invention may be used for laundry cleaning, hard surface cleaning (including cleaning of lavatories, kitchen work surfaces, floors, mechanical ware washing etc.). As is generally known in the art, bleaching compositions are also employed in waste-water treatment, pulp bleaching during the manufacture of paper, leather manufacture, dye transfer inhibition, food processing, starch bleaching, sterilisation, whitening in oral hygiene preparations and/or contact lens disinfection.
In the context of the present invention, bleaching should be understood as relating generally to the decolourisation of stains or of other materials attached to or associated with a substrate. However, it is envisaged that the present invention can be applied where a requirement is the removal and/or neutralisation by an oxidative bleaching reaction of malodours or other undesirable components attached to or otherwise associated with a substrate. Furthermore, in the context of the present invention bleaching is to be understood as being restricted to any bleaching mechanism or process that does not require the presence of light or activation by light.
Throughout the description and claims generic groups have been used, for example alkyl, alkoxy, aryl. Unless otherwise specified the following are preferred group restrictions that may be applied to generic groups found within compounds disclosed herein:
alkyl: linear and branched C1-C8-alkyl,
alkenyl: C2-C6-alkenyl,
cycloalkyl: C3-C8-cycloalkyl,
aryl: selected from homoaromatic compounds having a molecular weight under 300,
heteroaryl: selected from the group consisting of: pyridinyl; pyrimidinyl; pyrazinyl; triazolyl; pyridazinyl; 1,3,5-triazinyl; quinolinyl; isoquinolinyl; quinoxalinyl; imidazolyl; pyrazolyl; benzimidazolyl; thiazolyl; oxazolidinyl; pyrrolyl; carbazolyl; indolyl; and isoindolyl, wherein the heteroaryl may be connected to the compound via any atom in the ring of the selected heteroaryl,
heterocycloalkyl: selected from the group consisting of: pyrrolinyl; pyrrolidinyl; morpholinyl; piperidinyl; piperazinyl; hexamethylene imine; 1,4-piperazinyl; tetrahydrothiophenyl; tetrahydrofuranyl; 1,4,7-triazacyclononanyl; 1,4,8,11-tetraazacyclotetradecanyl; 1,4,7,10,13-pentaazacyclopentadecanyl; 1,4-diaza-7-thiacyclononanyl; 1,4-diaza-7-oxa-cyclononanyl; 1,4,7,10-tetraazacyclododecanyl; 1,4-dioxanyl; 1,4,7-trithiacyclononanyl; tetrahydropyranyl; and oxazolidinyl, wherein the heterocycloalkyl may be connected to the compound via any atom in the ring of the selected heterocycloalkyl,
carboxylate derivative: the group xe2x80x94C(O)OR, wherein R is selected from: hydrogen; C1-C6-alkyl; phenyl; C1-C6-alkyl-C6H5; Li; Na; K; Cs; Mg; and Ca,
Unless otherwise specified the following are more preferred group restrictions that may be applied to groups found within compounds disclosed herein:
alkyl: linear and branched C1-C6-alkyl,
alkenyl: C3-C6-alkenyl,
cycloalkyl: C6-C8-cycloalkyl,
aryl: selected from group consisting of: phenyl; biphenyl; naphthalenyl; anthracenyl; and phenanthrenyl,
heteroaryl: selected from the group consisting of: pyridinyl; pyrimidinyl; quinolinyl; pyrazolyl; triazolyl; isoquinolinyl; imidazolyl; and oxazolidinyl, wherein the heteroaryl may be connected to the compound via any atom in the ring of the selected heteroaryl,
heterocycloalkyl: selected from the group consisting of: pyrrolidinyl; morpholinyl; piperidinyl; piperidinyl; 1,4-piperazinyl; tetrahydrofuranyl; 1,4,7-triazacyclononanyl; 1,4,8,11-tetraazacyclotetradecanyl; 1,4,7,10,13-pentaazacyclopentadecanyl; 1,4,7,10-tetraazacyclododecanyl; and piperazinyl, wherein the heterocycloalkyl may be connected to the compound via any atom in the ring of the selected heterocycloalkyl,
carboxylate derivative: the group xe2x80x94C(O)OR, wherein R is selected from hydrogen; Na; K; Mg; Ca; C1-C6-alkyl; and benzyl,